Add tracing AutoOpenCloseEvent.

base/trace_event/video_playback_pae.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_TRACE_EVENT_VIDEO_PERSISTENT_ASYNC_H_
+#define BASE_TRACE_EVENT_VIDEO_PERSISTENT_ASYNC_H_
+
+#include "base/macros.h"
+#include "base/time/time.h"
+#include "base/trace_event/persistent_async_event.h"
+
+namespace base {
+
+namespace trace_event {
+
+// A persistent async event for video playback.
+

[charliea (OOO until 10-5), 2016/09/08 18:26:34]

nit: please delete extra line

[alexandermont, 2016/09/14 00:09:08]

Done

+class BASE_EXPORT VideoPlaybackPersistentAsyncEvent
+    : public PersistentAsyncEvent {
+ public:
+  VideoPlaybackPersistentAsyncEvent();
+  ~VideoPlaybackPersistentAsyncEvent() override;
+
+ protected:
+  void RecordBeginEvent() override;
+  void RecordBeginEventWithTimestamp(base::TimeTicks timestamp) override;
+  void RecordEndEvent() override;
+};
+
+}  // namespace trace_event
+}  // namespace base
+
+#endif  // BASE_TRACE_EVENT_VIDEO_PERSISTENT_ASYNC_H_